dear friend .
this is a big aim to learn embedded systems.
you shuld have to learn that how to tore this aim into pieces.
you should go through
1) transistor as switch.
2) logic gates
4) multivibrator (astable , mono, bi)
5) flip flop
6) registers
7) binary numbers, hex numbers(counting, +,-)
8) introduction about microprocessores
9) introduction about (atmel , pic , avr )microcontroller.
10) assymboly or high level language.
no 1 to 6 are important theoretically and practically but no 1 is most important .
then study about registers, binary numbers, hes numbers and conversion between them. conversion is very important.
study of microprocessor is partially required only theoretically .
then take an introduction about microcontroller families and choose any one.
choose your language .
think goals and achieve them. in starting you will on/off a led then relay, switches, lcd and so on.
later joint these things and make any thing you want.